Percutaneous Implantable Nuclear Prosthesis

ABSTRACT

An inter-vertebral disc prosthesis intended for percutaneous deployment comprises an expandable annular enclosure and an expandable nuclear enclosure. The expandable annular enclosure incorporates a reinforcing annular band along its periphery and is filled with in-situ curable rubber. The expandable nuclear enclosure is filled with a gas. The nuclear prosthesis further incorporates a novel, integrally molded sealing valve assembly and is stretchable and collapsible into a minimal profile for ease of insertion into a specially designed delivery cannula, and is inflation-assisted expandable into an inter-vertebral disc in which complete percutaneous nuclectomy has been performed.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a utility application claiming priority to U.S. ProvisionalApplication Ser. No. 61/212,104 filed Apr. 7, 2009, and incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to body-implantable devices.More particularly, the present invention relates to a percutaneouslyinsertable and expandable inter-vertebral disc prosthesis. Specifically,the present invention comprises a novel nuclear prosthesis, a speciallydesigned delivery apparatus, and a loading apparatus for loading thenuclear prosthesis within the delivery apparatus.

2. Description of the Related Art

The role of the inter-vertebral disc in spine biomechanics has been thesubject of extensive research and is generally well understood. Atypical native spinal unit is shown for exemplary purposes in FIG. 22A.The functional spinal unit, or spinal motion segment 500 consists of twoadjacent vertebrae 502 and 504, the inter-vertebral disc 506 and theadjacent ligaments (not shown). The components of the disc are thenucleus pulposus 506 a, the annulus fibrosis 506 b, and the vertebralend-plates 506 c. These components act in synchrony and their integrityis crucial for optimal disc function. During axial loading of the normalnative disc 506, the pressure of the nucleus pulposus 506 a rises,transmitting vertical force on the end plates 506 c and outward radialstress on the annulus fibrosis 506 b, as shown by the direction arrowsin FIG. 22A. The vertical stress is transformed to tensile forces in thefibers of the annulus fibrosis 506 b. Because the gelatinous nucleuspulposus 506 a is deformable but noncompressible, it flattens radially,and the annulus fibrosis 506 b bulges and stretches uniformly. Flexionof the spine involves the compression of the anterior annulus fibrosis506 b, as well as the nucleus pulposus 506 a. The nucleus pulposus 506 adeforms and migrates, posteriorly stretching the annular fibers andexpanding radially. Thus, the nucleus pulposus 506 a and annulusfibrosis 506 b function synergistically as a cushion by reorientingvertical forces radially in a centrifugal direction.

The native vertebral end plate 506 c prevents the nucleus pulposus frombulging into the adjacent vertebral body by absorbing considerablehydrostatic pressure that develops from mechanical loading of the spine.The end plate 506 c is a thin layer of hyaline fibrocartilage withsubchondral bone plate, typically around 1 millimeter thick. The outer30% of the end plate 506 c consists of dense cortical bone and is thestrongest area of the end plate 506 c. The end plate 506 c is thinnestand weakest in the central region adjacent to the nucleus pulposus.

With aging and repetitive trauma, the components of the inter-vertebraldisc 506 undergo biochemical and biomechanical changes and can no longerfunction effectively, resulting in a weakened inter-vertebral disc 506.As the disc 506 desiccates and becomes less deformable, the physical andfunctional distinction between the nucleus pulposus 506 a and theannulus fibrosis 506 b becomes less apparent. Disc desiccation isassociated with loss of disc space height and pressure. The annulusfibrosis 506 b loses its elasticity. The apparent strength of thevertebral end-plates 506 c decreases and vertebral bone density andstrength are diminished. This leads the end-plates 506 c to bow into thevertebral body, imparting a biconcave configuration to the vertebralbody. Uneven stresses are created on the end plates 506 c, annulusfibrosis 506 b, ligaments (not shown), and facet joints (not shown),leading to back pain. At this point, the annulus fibrosis 506 b assumesan inordinate burden of tensile loading and stress, and this furtheraccelerates the process of degeneration of the annulus fibrosis 506 b.Fissuring of the annulus fibrosis 506 b further diminishes its elasticrecoil, preventing the annulus fibrosis 506 b from functioning as ashock absorber. Leakage of the nuclear material can cause irritation ofthe nerve roots by both mechanical and biochemical means. Eventually,degenerative instability is created, leading to both spinal canal andneuroforaminal stenosis.

Historically, spine surgery consisted of simple decompressiveprocedures. The advent of spinal fusion and the proliferation ofsurgical instrumentation and implants has led to an exponentialutilization of expensive new technologies. As an alternative to opensurgical discectomy and fusion, Minimally Invasive Spinal Surgery (MISS)has been advocated. Thus far, the primary rationale for favoring theMISS approach has been to lessen postoperative pain, limit thecollateral damage to the surrounding tissues, and hasten the recoveryprocess rather than affect long term outcomes. Despite the lack of clearsuperiority and outcome data, these technologies have continued toflourish.

However, many spinal surgeons remain skeptical about the positive claimsregarding MISS, citing certain drawbacks, including increase inoperating room time, requirement for expensive proprietary instruments,increased cost, and the technically demanding nature of the procedure.Despite the advantage of a minimal incision approach, MISS requires anadequate decompression and/or fusion procedure in order to have resultscomparable to traditional open surgical approaches.

Ideally, a nuclectomy and implant insertion would be performed through apercutaneous posterolateral approach. Advantages of the percutaneousposterolateral approach over conventional open surgery and MISS includeobviating the need for surgically exposing, excising, removing, orinjuring interposed tissues; preservation of epidural fat; avoidingepidural scarring, blood loss, and nerve root trauma. Other advantagesinclude minimizing “access surgery” and hospitalization costs, andaccelerating recovery. A percutaneous procedure may be expeditiouslyused on an outpatient basis in selected patients. On the other hand,percutaneous insertion imposes a number of stringent requirements on thenuclear prosthesis and its method of delivery.

Several devices have been used to fill the inter-vertebral space voidfollowing discectomy in order to prevent disc space collapse. Thesedevices generally fall into two categories: fusion prostheses and motionprostheses. Fusion prostheses intended for MISS insertion offer few ifany advantages over those for open surgical technique. While these typesof implants eliminate pathological motion, they also prevent normalbiomechanical motion at the treated segment. Greater degrees of stressare transmitted above and below the treated segment, often leading toaccelerated degeneration of adjacent discs, facet joints, and ligaments(adjacent level degeneration).

Motion prostheses generally aim at restoring disc height, shockabsorption, and range of motion, thus alleviating pain. Artificialmotion prostheses may be divided into two general types: the total discprosthesis and the nucleus prosthesis. The total disc prosthesis isdesigned for surgical insertion, replacing the entire disc, while thenucleus prosthesis is designed for replacing only the nucleus pulposus,and generally may be inserted by open surgical or MISS methods.

Prior designs of motion nucleus prostheses include enclosures that arefilled with a diverse variety of materials to restore and preserve discspace height while permitting natural motion. However, there are severalshortcomings of prior nucleus motion prostheses designs. Some of theprior nucleus motion prostheses require surgical approaches forinsertion that involve removal of a significant amount of structuralspinal elements including the annulus fibrosis. Removal of thesestructural spinal elements causes destabilization of the spinal segment.Prior nuclear motion prosthesis designs also fail to provide the outermargin of the nuclear prosthesis with surface and structural propertiesthat encourage native tissue ingrowth. Instead, such prostheses are madefrom generally non-porous materials that impede full incorporation ofthe nuclear prosthesis into the surrounding annular margin.

Some prior designs have annular bands along the outer periphery of thenucleus motion prostheses. However, prior annular bands arenon-compliant. This is disadvantageous because it reduces the radialouter expansion required for load dampening. Thus, the load istransferred to the end plates of the vertebrae, which can withstand onlylimited deformation. The result is that the end plates eventually fail,resulting in loss of intradiscal pressure, accelerated degeneration, andsubsidence of the nuclear prosthesis. Other prostheses do not have anannular band. These prostheses tend to exert untoward pressure on analready weakened armulus fibrosis. Particularly, such a prosthesis tendsto protrude into a pre-existing annular tear.

Other designs fail to incorporate or use a central gas cushion with avalve system or assembly that does not leak. Still others concentratethe harder load bearing component of the nuclear prosthesis in thecentral aspect of the disc, predisposing the nuclear prosthesis tosubsidence. Another problem with prior nuclear motion prostheses is theimprecise sizing and tailoring of the nuclear prosthesis. Over sizingplaces unnecessary stress on the already damages and degenerated annulusfibrosis, while under sizing of the nuclear prosthesis may result ininadequate contact with the inner wall of the annulus fibrosis, andpossibly non-integration and migration of the nuclear prosthesis. Otherdesigns of nucleus motion prostheses suffer draw backs such asbulkiness, inelasticity, inability to fold and pack the nuclearprosthesis into a delivery cannula or apparatus for percutaneousimplantation into a patient. In fact, percutaneous delivery of a motionnucleus prosthesis heretofore, has been unavailable.

Applicants here propose to overcome the disadvantages of the priordesigns of nucleus motion prostheses by providing a multi-compartmentnuclear prosthesis having a semi-compliant annular reinforcement banddisposed adjacent or contiguously around the periphery of a rubberfilled annular enclosure. The annular enclosure nests a central, gascushioned nuclear enclosure and an integrated sealing valve assembly.The nuclear prosthesis of the present invention is foldable to fitwithin a delivery apparatus, and is intended for percutaneous insertioninto a nuclear space void following percutaneous total nuclectomy. Oncepercutaneously inserted, the nuclear prosthesis is expandable by aninflation-assisting device to provide cushioning and stability to aspinal segment weakened by degeneration.

SUMMARY OF THE INVENTION

The present invention overcomes the deficiencies of prior nuclear motionprostheses, offers several advantageous properties, and provides asystem for sizing, forming, delivering, and deploying a nuclearprosthesis into the inter-vertebral disc space. The percutaneouslyimplantable nuclear prosthesis, formed in accordance with the presentinvention, utilizes the advantages of both a textile prosthesis and apolymer prosthesis to create a compartmentalized composite structure,having characteristics closely resembling the properties of a healthynative inter-vertebral disc. The nuclear prosthesis is comprised of anannular structure and a nuclear structure. The annular structurecomprises an annular enclosing layer which defines an annular enclosure,an annular reinforcement band adjacent the periphery of the annularenclosing layer, a sealing valve core disposed within the annularenclosure and adjacently attached to the annular enclosing layer, andin-situ curable rubber, which is injected into the annular enclosure.The nuclear structure comprises a nuclear enclosing layer which definesa nuclear enclosure and an indwelling catheter mounted and bonded to aneck portion of the nuclear enclosing layer, and extends distally into,and is enclosed within the nuclear enclosure.

Referring to FIG. 22B the structure of the nuclear prosthesis comprisingthe annular structure 11 filled with the deformable, but notcompressible in-situ curable rubber and the nuclear structure 21centrally located within the annular structure 11 and being filled witha compressible gas allows for the vertical and horizontal load stressesplaced on the inter-vertebral disc space to be redirected inward,centrally toward the nuclear structure 21 (see direction arrows of FIG.22B), instead of outward. Moreover, annular structure 11 has abiocompatible outer annular reinforcement band that encourages tissuein-growth of the native annulus fibrosis 506 b, thereby providingreinforcement to the native annulus fibrosis.

According to the present invention, there is provided a percutaneouslyinsertable and detachable nuclear prosthesis having an annular enclosinglayer that defines an annular enclosure. The annular enclosing layer ismade of an annular tubular elastomeric membrane, is contiguous along itsouter periphery with a textile annular reinforcement band, andincorporates a sealing valve core. Central to the annular enclosinglayer is a nuclear enclosing layer defining a nuclear enclosure. Thenuclear enclosing layer has a neck region. The neck region of thenuclear enclosing layer defines an open mouth that receives anindwelling catheter. The neck region is mounted on the indwellingcatheter. The indwelling catheter is a tube that defines a lumen. Theindwelling catheter is coupled to a sealing valve core which is disposedwithin the annular enclosure, and has its lumen plugged by a sealingplug after inflation within the inter-vertebral disc space.

The nuclear prosthesis is detachably mounted to a distal end of aninflation stylus and is loaded within a distal end of a deliveryapparatus. The inflation stylus has three inflation tubes projectingfrom the distal end of the inflation stylus and slidably insertablethrough the sealing valve core of the sealing valve assembly. Thesealing valve core is formed of a resilient material and has threepathways being defined by three parallel channels extended through thesealing valve core. Upon insertion of the three inflation tubes of theinflation stylus through the channels of the sealing valve core, thepathways take the form of cylindrical apertures in precise matingalignment with the inflation tubes of the inflation stylus to providefluid-tight seal against and around the outer surfaces of the inflationtubes. The central inflation tube is a nuclear access tube that providespressurized fluid to the nuclear enclosure. One of the outer tubes is anannular inlet tube that provides pressurized fluid to the annularenclosure through an inlet port provided in the sealing valve core. Theother outer tube is an annular outlet tube that receives pressurizedfluid from the annular enclosure through an outlet port provided in thesealing valve core.

The annular inlet tube and the annular outlet tube have side pores inthe walls of the tubes adjacent the closed tips of the tubes wherebyin-situ vulcanizing rubber flows through the side pore in the annularinlet tube into one end of the annular enclosure and back through theside pore of the annular outlet tube, and into the inflation stylus.After inflation of the annular enclosure and nuclear enclosure, theinflation stylus can be efficiently disengaged from the sealing valvecore, and upon withdrawal thereof, the pathways return to an elongatedslit or channel configuration to provide a fluid tight seal for theinflated nuclear prosthesis.

It is, therefore, a general object of the present invention to provide anuclear prosthesis which exhibits an optimal overall combination ofphysical, viscoelastic, and other properties superior to previousdesigns of motion nucleus prostheses.

It is another object of the present invention to provide a nuclearprosthesis that is fundamentally reliable and durable, and utilizes thelatest in surface modification technology to enhance thebio-compatibility, bio-durability, infection resistance, and otheraspects of performance.

It is another object of the present invention to provide a nuclearprosthesis that reduces stress on the vulnerable central portions of thenative vertebral end plates.

It is another object of the present invention to reduce the stress onthe vulnerable central portions of the native vertebral end plates byproviding a nuclear prosthesis that redirects the vector of forcescaused by load stress inward, toward the core or center of the nuclearprosthesis. In this regard, the present invention provides a gas-filledcentral enclosure to aide in load bearing, cushioning, shock absorptionand stabilization by directing the vector of forces toward thegas-filled central enclosure. The present invention redirects bothlateral and vertical forces toward the gas-filled central enclosure,thereby providing protection to the vertebral end plates. The presentinvention accomplishes the redirection of vector forces by having anon-compliant annular reinforcement band along the outer periphery ofthe nuclear prosthesis, and a compressible gas filled central nuclearenclosure.

It is yet another object of the present invention to provide a nuclearprosthesis that provides reinforcement and structural support to thenative annulus fibrosis. The annular reinforcement band of the presentinvention encourages native tissue in-growth of the native annulusfibrosis to provide added stabilization and reinforcement.

It is still another object of the present invention to provide a nuclearprosthesis wherein the compliance of the nuclear prosthesis increasesprogressively toward the center of the nuclear prosthesis. Eachcomponent of the nuclear prosthesis is tailored to provide suitableviscoelastic properties that contribute to the overall performance ofthe nuclear prosthesis. This arrangement is intended to relieve thestress on the native annulus fibrosis by redirecting the radial outervector of forces centrally toward the nuclear enclosure. The nuclearprosthesis is thus rendered iso-elastic with respect to the spinalsegment.

Yet another object of the present invention is to provide a nuclearprosthesis that has expansion tailorability. The nuclear prosthesis canbe expanded to variable sizes to accommodate the dimensions of theevacuated nuclear space. The nuclear enclosing layer, annular enclosinglayer and annular reinforcement band possess the ability to be firstinflated or stretched to its unextended or working profile and then,there-beyond to a limited extent and/or controlled extent by theapplication of greater pressure. The controlled flexibility of thetextile annular reinforcement band and the expansion of the annular andnuclear enclosures can accommodate a wider range of nuclear spacedimensions, reducing the need to precisely match the nuclear prosthesisto the nuclear space as to size.

It is yet a further object of the present invention to provide aninflation-assisted expandable nuclear prosthesis that distracts the discspace, and supports and reinforces the annulus fibrosis while keepingthe ligaments and facet joints in a taut condition.

It is another object of the present invention to provide a novel sealingvalve assembly which has a sealing valve core integrally bonded to theannular enclosing layer within the annular enclosure, having a mountingregion adapted on its inner margin for fluid tight bonding to anindwelling catheter lying within the nuclear enclosure. The sealingvalve core of the sealing valve assembly is detachably connected to thetip of the delivery apparatus and is self-sealing upon removal of theinflation stylus.

It is another object of the present invention to provide a nuclearprosthesis which can be geometrically and elastically deformed to reduceits axial and transverse diameter through radial elongation, into aminimal profile for ease of insertion into the delivery apparatus, whileminimizing the risks that could be associated with such flexibility.This is achieved by the components of the nuclear prosthesis beingsuitably configured and dimensioned to form a perfect mating fit to eachother and to the nuclear enclosing layer. The annular reinforcementlayer, annular enclosing layer and nuclear enclosing layer mustcooperate in a synchronized fashion to achieve a precise folded andwrapped configuration. The folding of the nuclear prosthesis is furtherachieved by minimizing the combined thicknesses of the annular enclosinglayer and nuclear enclosing layer and optimizing the longitudinalflexibility and radial compliance of the annular reinforcement band bycareful selection of the type of bio-compatible yarn, the number oflayers, the heat set conditions, and the angles at which braids areformed. The folding of the nuclear prosthesis is also aided by theselection and use of a semi-compliant medical balloon material for theannular and nuclear enclosing layers.

It is further an object of the present invention to provide a nuclearprosthesis that has a porous outer margin thereby facilitating theincorporation of the nuclear prosthesis into the nuclear space.

It is yet another object of the present invention to provide a deliveryapparatus having an assembly of coaxial telescoping cannulas with thenuclear prosthesis disposed therein, and a method of delivering thenuclear prosthesis percutaneously to the nuclear space. The deliveryapparatus houses and carries the folded nuclear prosthesis within itsdelivery cannula. The delivery cannula also houses and incorporates aninflation stylus defining three tubes in fluid communication with thethree chambers or pathways of the sealing valve core of the nuclearprosthesis. Within the delivery cannula is a specially designed releasecannula adjacent the sealing valve core to release the inflation stylusfrom the nuclear prosthesis.

A typical procedure for implantation of the nuclear prosthesis involvesperforming an initial percutaneous nuclectomy through a percutaneousaccess device, insertion of the delivery apparatus within thepercutaneous access device, insertion of the delivery cannula carryingthe nuclear prosthesis and deploying the nuclear prosthesis within thenuclear space void. In deployment, the annular and nuclear enclosuresare expanded using any suitable fluid delivery system, allowing thenuclear prosthesis to assume a substantially discoid shape as thenuclear prosthesis radially and axially expands and substantiallyconforms to the shape of the nuclear space void.

The annular and nuclear enclosures are inflated simultaneously with apressurized liquid until adequate disc space distraction is achieved anda predetermined pressure level within the nuclear prosthesis isachieved. The annular enclosure is inflated with an in-situ curablerubber, and the nuclear enclosure is inflated with a liquid such assaline. After curing of the in-situ curable rubber within the annularenclosure occurs, the liquid within the nuclear enclosure is replacedwith a compressible gas. Nitrogen, carbon dioxide, or many othersuitable gases can be used within the nuclear enclosure. At this point,the indwelling catheter is plugged with a sealing plug introduced intothe indwelling catheter and pushed therein. The delivery cannula isdetached from the sealing valve core by the release cannula, and thedelivery apparatus is then removed.

These and other objects, aspects, features and advantages of the presentinvention will be clearly understood and explained with reference to theaccompanying drawings and through consideration of the followingdetailed description.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view of the annular structure of the nuclearprosthesis of the present invention;

FIG. 1A is a sectional side view of the loading apparatus of the presentinvention with an inflated nuclear prosthesis of the present inventiontherein;

FIG. 1B is a sectional side view of an inflated annular enclosing layerof the nuclear prosthesis of the present invention;

FIG. 1C is a sectional side view of an inflated annular enclosing layerof the nuclear prosthesis of the present invention;

FIG. 1D is a sectional top view of the delivery apparatus of the presentinvention with the nuclear prosthesis of the present invention loadedtherein;

FIG. 2 is a sectional side view of an inflated annular enclosing layerand deflated nuclear enclosing layer of the nuclear prosthesis of thepresent invention;

FIG. 2A is a sectional side view of the loading apparatus of the presentinvention with a partially deflated nuclear prosthesis of the presentinvention therein;

FIG. 2B is a sectional side view of the annular enclosing layer of thenuclear prosthesis of the present invention in a partially stretchedposition during loading into the delivery apparatus;

FIG. 2C is a sectional side view of the nuclear prosthesis of thepresent invention in a partially deflated state;

FIG. 2D is a sectional top view of the delivery apparatus of the presentinvention with the nuclear prosthesis of the present invention loadedthereon;

FIG. 3 is a sectional side view of the nuclear prosthesis and theinflation stylus of the present invention;

FIG. 3A is a sectional side view of the loading apparatus of the presentinvention showing the loading of a deflated nuclear prosthesis of thepresent invention onto the delivery apparatus of the present invention;

FIG. 3B is a sectional side view of the annular enclosing layer of thenuclear prosthesis of the present invention in a fully stretchedposition during loading onto the delivery apparatus;

FIG. 3C is a sectional side view of the nuclear prosthesis showing thefolding of the annular enclosing layer around the nuclear enclosinglayer when the nuclear prosthesis is deflated;

FIG. 3D is a sectional top view of the delivery apparatus of the presentinvention with the nuclear prosthesis of the present invention loadedthereon and retracted therein, with the delivery apparatus disposedwithin an access cannula;

FIG. 4 is a sectional top view of the nuclear prosthesis and theinflation stylus of the present invention;

FIG. 5 is a sectional top partially exploded view of the sealing valvecore of the sealing valve assembly of the nuclear prosthesis of thepresent invention;

FIG. 6 is a sectional top view of the sealing valve core of the sealingvalve assembly of the nuclear prosthesis of the present invention;

FIG. 7 is a sectional top view of the sealing valve core of the sealingvalve assembly of the nuclear prosthesis of the present invention;

FIG. 8 is a side view of the indwelling catheter and the mounting regionof the nuclear enclosing layer of the nuclear prosthesis of the presentinvention;

FIG. 9 is a sectional side view of the annular enclosing layer,retaining ring and the layers of the annular reinforcement band of thenuclear prosthesis of the present invention;

FIG. 10 is a sectional side view of the inflation stylus of the presentinvention and the of the nuclear prosthesis of the present inventionshowing interaction of the nuclear access tube with the indwellingcatheter;

FIG. 11 is a sectional top view of the inflation stylus of the presentinvention;

FIG. 11A is a sectional top view of the inflation stylus of the presentinvention and the of the nuclear prosthesis of the present inventionshowing interaction of the tubes of the inflation stylus with the portsand pathways of the sealing valve core;

FIG. 11B is a sectional top view of the inflation stylus of the presentinvention and the of the nuclear prosthesis of the present inventionshowing interaction of the tubes of the inflation stylus with the portsand pathways of the sealing valve core;

FIG. 12 is a side view of the release cannula of the delivery apparatusof the present invention interacting with the annular enclosing layer ofthe nuclear prosthesis of the present invention;

FIG. 13 is a side view along line 12-12 of FIG. 12 showing theconnection of the inflation stylus to the of the nuclear prosthesis ofthe present invention;

FIG. 14 is a sectional side view showing the connection of the inflationstylus to the of the nuclear prosthesis of the present invention;

FIG. 15 is a sectional side view showing the connection of the inflationstylus to the of the nuclear prosthesis of the present invention;

FIG. 16 is a sectional side view showing the annular enclosing layerfolded around the nuclear enclosing layer when the is a sectional sideview showing the connection of the inflation stylus to the of thenuclear prosthesis of the present invention is deflated;

FIG. 17 is a perspective view of the outer layer of the annularreinforcement band of the nuclear prosthesis of the present invention;

FIG. 18 is a perspective view of one of the middle layers of the annularreinforcement band of the nuclear prosthesis of the present invention;

FIG. 19 is a perspective view of the inner layer of the annularreinforcement band of the nuclear prosthesis of the present invention;

FIG. 20 is a sectional side view of the nuclear prosthesis of thepresent invention after delivery and inflation with fluid within thepatient;

FIG. 21 is a sectional side view of the nuclear prosthesis of thepresent invention after delivery and inflation with fluid within thepatient;

FIG. 22A is a rear view of a native inter-vertebral disc space showingthe direction of dispersion of typical horizontal and vertical loadforces; and

FIG. 22B is a rear view of an inter-vertebral disc space with thenuclear prosthesis of the present invention therein, showing redirectionof dispersion of typical horizontal and vertical load forces by thenuclear prosthesis of the present invention.

DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 through 4 the nuclear prosthesis 10 of the presentinvention is disclosed. Nuclear prosthesis 10 comprises an annularstructure 11 and a nuclear structure 21. Annular structure 11 comprisesan annular enclosing layer 12 defining an annular enclosure 14, andnuclear structure 21 comprises a nuclear enclosing layer 22 defining anuclear enclosure 24. Nuclear enclosing layer 22 is disposed adjacentannular enclosing layer 12 in the central space defined by annularenclosing layer 12, along an inner margin 16 thereof. Annular structure11 of nuclear prosthesis 10 further comprises an annular reinforcementband 20 contiguous with or adjacent a peripheral or outer margin 18 ofthe inflatable annular enclosing layer 12 and a sealing valve core 28 ofa sealing valve assembly 26. Annular enclosing layer 12 incorporates thesealing valve core 28 and annular enclosure 14 filled in-situ withcurable rubber. In its inflated state, nuclear prosthesis 10 issubstantially discoid in shape, as shown in FIGS. 20 and 21.

Annular enclosure 14 is in communication with an inlet port 36 a and anoutlet port 38 a of sealing valve core 28. Nuclear structure 21comprises nuclear enclosing layer 22, which defines a discoid inflatablenuclear enclosure 24, and an indwelling catheter 32. A neck portion 22 aof nuclear enclosing layer 22 is mounted on indwelling catheter 32,which has a side-pore 32 a and a closed tip 32 d (see FIG. 8). Nuclearenclosing layer 22 is filled in-situ with compressible gas and convergeson a neck portion 22 a adapted for fluid-tight bonding to indwellingcatheter 32 (see FIG. 8). Returning to FIGS. 1 through 4, indwellingcatheter 32 includes a bulbous portion 32 b on the proximal end thereof,which is adapted to be coupled within a sealing valve core 28 of sealingvalve assembly 26 to a pressurized fluid for inflation of nuclearenclosure 24. Bulbous portion 32 b of indwelling catheter 32 issnap-secured and adhesively bonded to sealing valve core 28 so that afluid-tight connection will be achieved.

Referring to FIGS. 1D, 2D and 3D, a delivery apparatus 200 is disclosed.Delivery apparatus 200 is coaxially and telescopically slidable withinan access cannula 202. A distal delivery cannula 204 of deliveryapparatus 200 coaxially encloses a release cannula 206 (see FIGS. 10,11A, 11B and 12) and an inflation stylus 100. Referring to FIGS. 4, 11,11A and 11B, inflation stylus 100 is a rigid tube with a triple lumenthat terminates in three inflation tubes 102, 104 and 106. Inflationtubes 102, 104 and 106 define inflation lumens therein, and are in fluidcommunication with annular enclosure 14 and nuclear enclosure 24 viasealing valve core 28. The three inflation tubes are an annular inlettube 102, an annular outlet tube 104 and a nuclear access tube 106.Annular inlet tube 102, annular outlet tube 104 and nuclear access tube106 project from the distal end of inflation stylus 100 and aredetachably secured to three corresponding pathways 36 b, 38 b and 40,respectively, within sealing valve core 28.

Inflation tubes 102, 104 and 106 are adapted to mate with the threecorresponding pathways 36 b, 38 b and 40, respectively, of sealing valvecore 28. In order to couple inflation stylus 100 to sealing valve core28, inflation tubes 102, 104 and 106 are inserted through the inflationbores 36 c, 38 c and 40 a, respectively, which are disposed on the outermargin of sealing valve core 28 (see FIGS. 12 through 14). Inflationtubes 102, 104 and 106 then extend into the slit-like pathways 36 b, 38b and 40, respectively.

A fluid-tight communication is formed between annular enclosure 14through inlet port 36 a and outlet port 38 a, and through annular inlettube 102 and annular outlet tube 104. Annular inlet tube 102 has a sidepore 102 a, and annular outlet tube 104 has a side pore 104 a. Sidepores 102 a and 104 a are located towards the closed distal ends of theannular inlet tube 102 and annular outlet tube 104, respectively. Sidepore 102 a provides a fluid-tight communication with inlet port 36 a,and side pore 104 a provides a fluid-tight communication with outletport 38 a of sealing valve core 28. A third fluid-tight communication isformed between nuclear enclosure 24 and inflation stylus 100, throughnuclear access tube 106, which terminates with an end bore 106 a.Nuclear access tube 106 slides through passage 40 a and engages aproximal end 32 c of indwelling catheter 32.

Referring to FIGS. 4 through 9, 11A and 11B, the design of sealing valveassembly 26 is disclosed. Sealing valve assembly 26 employs sealingvalve core 28 which permits the passage of fluid through inlet port 36a, outlet port 38 a and indwelling catheter 32, but prevents the flow offluid through sealing valve core 28 when tubes 102, 104 and 106 areremoved from pathways 36 b, 38 b and 40, respectively. Sealing valvecore 28 is formed of a resilient material and contains the threeconstricted slit-like pathways 36 b, 38 b and 40 for frictionallyengaging the outer surfaces of inflation tubes 102, 104 and 106,respectively, so that a predetermined force is required to withdrawinflation stylus 100 from sealing valve core 28. Pathways 36 b, 38 b and40 define passageways through which inflation tubes 102, 104 and 106,respectively, may be inserted without imparting damage to sealing valvecore 28.

Sealing valve assembly 26 comprises sealing valve core 28, indwellingcatheter 32, and a sealing plug (not shown). Sealing valve core 28 hasthe general cross-sectional configuration as inflated annular enclosure14, and is substantially concentric with inflated annular enclosinglayer 12. Sealing valve core 28 has an outside diameter which isslightly smaller than the diameter of inflated annular enclosure 14,allowing for additional thickness contributed by annular enclosing layer12 adjacently enclosing sealing valve core 28. The additional thicknessis crucial during loading nuclear prosthesis 10 onto delivery apparatus200. Sealing valve core 28 is preferably fabricated by molding fromimplantable grade elastomeric material (not shown), such that when anin-situ curable rubber such as RTV liquid silicon or other suitable RTVliquid elastomer is injected in-situ into annular enclosure 14, a strongbond is formed between the thermoset silicon of sealing valve core 28and in the in-situ cured rubber to create a unified load-bearingcushion. Preferably, both sealing valve core 28 and the in-situ curablerubber have a similar modulus of elasticity.

Referring to FIGS. 11A and 11B, sealing valve core 28 detachably mountedon the distal end of inflation stylus 100 is shown. Inflation tubes 102,104 and 106 at the distal end of inflation stylus 100 are insertedthrough pathways 36 b, 38 b and 40, respectively, of sealing valve core28. In this configuration, side pore 102 a of annular inlet tube 102 andside pore 104 a of annular outlet tube 104 are in alignment with inletport 36 a and outlet port 38 a, respectively, of the sealing valve core28. Pathways 36 b, 38 b and 40 in sealing valve core 28 aresubstantially collapsible such that they take the form of threeelongated slits prior to insertion of inflation tubes 102, 104 and 106therein.

Upon insertion of inflation tubes 102, 104 and 106 through pathways 36b, 38 b and 40, respectively, detachable fluid-tight engagement isachieved between inflation tubes 102, 104 and 106 of inflation stylus100, and annular enclosing layer 12 and nuclear enclosing layer 22.Pathways 36 b, 38 b and 40 frictionally engage the outer surfaces ofinflation tubes 102, 104 and 106, obviating the danger of leakage ordislodgement during the pressuring and inflation of nuclear prosthesis10, as will discussed in more detail hereinafter.

Referring to FIGS. 5 through 9, 11A and 11B, sealing valve core 28 formsan annular slot 28 b, which extends the outer radial circumference ofsealing valve core 28. Therefore, annular slot 28 b is adjacent bothinner margin 16 of annular enclosing layer 12 and outer margin 18 ofannular enclosing layer 12. Sealing valve core 28 further forms anuclear slot 28 a within annular slot 28 b along the surface of sealingvalve core 28 adjacent inner margin 16 of enclosing layer 12. Annularslot 28 b and nuclear slot 28 a are adapted to receive and retain innermargin 16 of annular enclosing layer 12, respectively, as well as asurrounding retaining ring 30. Thus, along inner margin 16, annular slot28 b and nuclear slot 28 a define a nuclear mounting region 28 d, whichreceives annular enclosing layer 12 and retaining ring 30 thereinAnnular slot 28 b is adapted to receive and retain outer margin 18 ofannular enclosing layer, as well as retaining ring 30. Therefore, alongouter margin 18, annular slot 28 b defines an annular mounting region 28c for receiving and retaining outer margin 18 of enclosing layer andretaining ring 30. The lateral ridges of annular slot 28 b along outermargin 18 of annular enclosing layer 12 mate with a flat distal tip ofrelease cannula 206 of delivery apparatus 200 such that when releasecannula 206 is held stationary and inflation stylus 100 is retracted,release cannula 206 urges sealing valve core 28 to detach from inflationstylus 100.

Referring to FIGS. 2, 3, 4, and 8, nuclear structure 21 comprisesnuclear enclosing layer 12, nuclear enclosure 24 and indwelling catheter32. Nuclear enclosure 24 is defined by the inflatable nuclear enclosinglayer 22, which is bonded about the periphery of indwelling catheter 32.Indwelling catheter 32 is comprised of a catheter body having a bulbousportion 32 b disposed on the proximal end 32 c of indwelling catheter32, which is affixed to inner margin 16 of annular enclosing layer 12,and extends within sealing valve core 28. Nuclear enclosing layer 22 isbonded to indwelling catheter 32 at a connector terminal 22 b. Connectorterminal 22 b is defined by neck portion 22 a receiving and tightlybonding to the body of indwelling catheter 32 at a predetermineddistance from proximal end 32 c and bulbous portion 32 b of indwellingcatheter 32, and a retaining collar 22 c receiving and crimping to neckportion 22 a and indwelling catheter 32 to provide a fluid-tight seal tonuclear enclosing layer 22.

A fluid-tight seal is formed between indwelling catheter 32 and neckportion 22 a of the nuclear enclosing layer 22 by applying a layer ofadhesive material (not shown) between indwelling catheter 32 and neckportion 22 a of nuclear enclosing layer 22 and crimping retaining collar22 c over indwelling catheter 32 and neck portion 22 a to form thesealed connector terminal 22 b. Preferably, indwelling catheter 32 andthe inner surface of neck portion 22 a are thermally and chemicallysimilar, allowing a permanent bond to be performed.

In a preferred embodiment, a polymeric insert (not shown) formed of amutually bondable material may be interposed between the outer surfaceof indwelling catheter 32 and inner surface of neck portion 22 a ofnuclear enclosing layer 22 during the manufacturing process; thusproviding for a more durable structural integrity of the attachment. Theentire connector terminal 22 b including retaining collar 22 c, which isplaced around neck portion 22 a of nuclear enclosing layer 22, is thenthermally processed and crimped to sealably bond neck portion 22 a ofnuclear enclosing layer 22 to indwelling catheter 32. Retaining collar22 c tapers proximally for ease of insertion and bonding into nuclearslot 28 a of nuclear mounting region 28 b. Indwelling catheter 32 isrelatively stiff and may be formed from polyurethane or polyethylenematerial (not shown) and may include a braided or helically wound wirereinforcing layer (not shown) to resist kinking. In a preferredembodiment, indwelling catheter 32 is formed by extruding a plurality oflayers (not shown), including a suitably bondable outer layer (notshown) into a tubular form.

A seal plug (not shown) is inserted into indwelling catheter 32 forobstructing the lumen of indwelling catheter 32 after inflation ofnuclear enclosure 24 is complete. The seal plug is prevented from beingdislodged from the lumen of indwelling catheter 32 by the constrictionof the slit-like pathway 40 of sealing valve core 28 followingretraction of inflation stylus 100.

Referring to FIGS. 1 through 3, and FIGS. 1B through 3C, annularenclosing layer 12 has a doughnut-configuration with a substantiallyconcave inner margin 16 and a substantially convex outer margin 18,providing for inward folding of the concave inner margin 16, forming asubstantially “C” shaped flat band upon deflation of nuclear prosthesis10. The substantially “C” shaped flat band configuration of the deflatedannular enclosing layer 12 facilitates wrapping annular enclosing layer12 around the collapsed nuclear enclosing layer 22 and indwellingcatheter 32. This configuration also provides for interlocking ofnuclear enclosing layer 22 within annular enclosing layer 22 whennuclear prosthesis 10 is inflated.

Annular enclosing layer 12 is preferably made from a polymeric materialand defines a fluid-tight annular enclosure 14, which is inflatable withan in-situ curable rubber. Annular enclosing layer 12 is preferablysemi-compliant. Desirable attributes of annular enclosing layer 12 arenot necessarily identical to desirable attributes for medical ballooncatheters (not shown), which are used extensively in medicalapplications such as angioplasty, valvuloplasty, urological proceduresand tracheal or gastric intubation.

For example, non-compliance and high tensile strength are less crucialin the case of the present invention's annular enclosing layer 12 ofnuclear prosthesis 10. Annular enclosing layer 12 is not expected to besubjected to high bursting pressures because annular enclosing layer 12is filled with curable in-situ rubber that is deformable, and becausenuclear prosthesis 10 is contained within the confines of a closed spacebordered by the native vertebral end-plates of the patient. Furthermore,annular enclosing layer 12 is disposed between annular reinforcementband 20 and nuclear enclosing layer 22, which restrain over-inflation ofannular enclosing layer 12, thus further making non-compliance and hightensile strength less crucial. The thickness of the membrane (not shown)of which annular enclosing layer 12 is made need only be thick enough toprovide a fluid-tight barrier to leakage of in-situ cured rubber.Accordingly, a thin membrane of 20 to 60 microns may be used toconstruct annular enclosing layer 12.

On the other hand, long-term structural integrity, moisture resistance(to avoid degeneration and to provide some protection to the rubberwithin annular enclosure 14) is of paramount importance to ensuredurability. Other desirable attributes include kink resistance, low wallthickness, low tendency for pinholing, and ease of bonding and coatingto other compounds.

Referring to FIGS. 4 through 9, 11A and 11B, sealing valve core 28 ofthe present invention is adapted to be disposed within annular enclosure14 and is bondable to annular enclosing layer 12 by heat fusion,ultrasonic welding, hot mold bonding, crimping, or other similar bondingmethods known in the art. Adhesive layers (not shown) may be usedadvantageously in combination to bond sealing valve core 28 of sealingvalve assembly 26 to annular enclosing layer 12, although when thepolymer material (not shown) of which sealing valve core 28 of sealingvalve assembly 26 and annular enclosing layer 12 are made are similar,adhesives may be unnecessary.

As annular enclosing layer 12 is made from semi-compliant material (notshown), inflating annular enclosure 14 tends to exert a peel-away forceon the bond between annular enclosing layer 12 and sealing valve core 28of sealing valve assembly 26. To avoid this potential problem, nuclearslot 28 a and annular slot 28 b are formed along the surface of sealingvalve core 28 adjacent inner margin 16 of annular enclosing layer 12,and are adapted to receive a portion of inner margin 16 of annularenclosing layer 12 and a portion of inner layer 30 a of retaining ring30. Annular slot 28 b extends the radial circumference of sealing valvecore 28. On the surface of sealing valve core 28 adjacent outer margin18 of annular enclosing layer 12, annular slot 28 b receives a portionof outer margin 18 and a portion of outer layer 30 b of retaining ring30. In a preferred embodiment, the method of securing sealing valve core28 of sealing valve assembly 26 to annular enclosing layer 12 includesthe use of retaining ring 30 positioned over and crimped tightly aroundannular enclosing layer 12 such that inner layer 30 a of retaining ring30 is adjacent nuclear slot 28 a, and outer layer 30 b of retaining ring30 is adjacent annular slot 28 b. The entire connection of sealing valvecore 28, annular enclosing layer 12 and retaining ring 30 is thenthermally pressed to form a sealably bonded sealing valve core 28 withinannular enclosure 14 resistant to separation from annular enclosinglayer 12 during inflation.

Preferably, both sealing valve core 28 and the in-situ curable rubberinjected into annular enclosure 14 are comprised of the same rubbermaterial. When the in-situ curable rubber injected in annular enclosure14 during inflation of nuclear prosthesis 10 solidifies, it bonds tosealing valve core 28. The result is that the distinction betweensealing valve core 28 and the curable rubber disappears, and an integralannular enclosure 14 of unitary construction is created.

Referring to FIGS. 4, 9, 10 and 17 through 19, annular reinforcementband 20 is disclosed. Annular reinforcement band 20 of the presentinvention is preferably a semi-compliant multi-layered bio-compatibletextile structure that provides a detent to maximal stretching of thecircumference of nuclear prosthesis 10. Various parameters andproperties of annular reinforcement band 20 may be adjusted to providelongitudinal flexibility and stretch, radial compliance, and kinkresistance of annular reinforcement band 20. Such variations includevarying the materials from which the fibers making up the layers 20 a,20 b and 20 c of annular reinforcement band 20 are formed, varying fiberdensity, varying fiber denier, varying braiding angles, varying thenumber of strands per filament, and varying heat-set conditions. Theseparameters are tailored to provide the desirable function required of aparticular layer of annular reinforcement band 20, depending on thelayer's position in annular reinforcement band 20. Generally, outerlayers 20 a should be substantially less compliant, and compliance theannular reinforcement band 20 should increase through intermediatelayers 20 b and inner layer 20 c.

In a preferred embodiment, annular reinforcement band 20 is athree-dimensional structure that is formed by extending and interlockingat least one yarn of each layer of annular reinforcement band 20 withthe adjacent layers. The multi-layered textile annular reinforcementband 20 shows a gradation of properties between its inner layers andouter layers. Referring to FIG. 9 and FIGS. 17 through 19, at least one,and preferably more than one outer layers 20 a are preferably made of awarp knitted pattern of biocompatible fibers. This gives outer layers 20a of annular reinforcement band 20 the advantage of velour, highporosity surface, enhancing tissue in-growth, as well as resistingunraveling. The fibers of outer layers 20 a may be of low denier and maybe textured or non-textured.

At least one, and preferably more than one intermediate layers 20 b maybe formed from biocompatible fibers forming a plurality of loops whichfollow helical or spiral paths, which may also be wavy or serpentine,contributing to the compliance of annular reinforcement band 20. Thefibers of intermediate layers 20 b preferably include monofilaments oflarger denier formed of durable material, such as polyethyleneteraphthlate in braided or jersey patterns providing a load-bearingcomponent, resistant to torsion and overstretching. The fibers inintermediate layers 20 b may be chosen to perform a gradation ofproperties between the mid or equatorial region of annular reinforcementband 20 towards the upper and lower axial margins thereof. In apreferred embodiment, the equatorial section of annular reinforcementband 20 is formed of monofilaments that are thicker, stronger and lesscompliant filaments, with tapering of these properties towards the upperand lower margins of annular reinforcement band 20. This renders annularreinforcement band 20 more resistant to kinking during stretching andradial compression of nuclear prosthesis 10 necessary to load nuclearprosthesis 10 within delivery apparatus 200.

Inner layer 20 c of annular reinforcement band 20 is formed from morecompliant and thinner biocompatible yarn. In one embodiment, inner layer20 c may include a fusible fiber (not shown) having a low meltingtemperature, heat-fusing annular reinforcement band 20 to an innermostlayer of intermediate layers 20 b and annular enclosing layer 12,enhancing ravel and fray resistance. In the preferred embodiment,annular reinforcement band 20 is not bonded to annular enclosing layer12.

In the preferred embodiment of the present invention, synthetic yarns(not shown) which are not degraded by the body are used to form thetextile annular reinforcement band 20. The yarns may be of themonofilament, multifilament or spun type, used in differentcombinations. Monofilaments are preferred in intermediate layers 20 b,providing for a lower volume structure with comparable strength to thefiber bundles of the multifilament fibers. Multifilaments are preferredalong inner layer 20 c and outer layers 20 a to increase flexibility.The yarns may be flat, textured, twisted, shrunk, or pre-shrunk. Asdiscussed above, the yarn type and yarn denier for a particular layer ofthe textile annular reinforcement band 20 may be chosen to meet thedesign requirements of annular reinforcement band 20.

Referring to FIGS. 2, 3 and 4, nuclear enclosing layer 22 is essentiallya discoid multilayered medical balloon which is fabricated by forming aplurality of polymeric layers (not shown) that converge on neck portion22 a of connector terminal 22 b, adapted for fluid-tight bonding toindwelling catheter 32. Conventional balloon fabricating techniques areutilized to form a composite nuclear enclosing layer 22 of differentpolymeric materials (not shown) that are subjected to a stretchblow-molding operation in a heated mold (not shown). The resultingnuclear enclosing layer 22 of the present invention provides superiorburst strength, superior abrasion resistance, and superior structuralintegrity, without significantly impairing the overall compressibilityand gas-cushioning function of nuclear prosthesis 10.

Long-term maintenance of a gas cushion in an inflated state is perhapsthe most demanding requirement of nuclear enclosure 24. Variousapproaches may be taken, including melt-blending the materials making upnuclear enclosing layer 22 and the use of multilayer fiber reinforcedballoon structures (not shown) to make nuclear enclosing layer 22.

Referring to FIGS. 2, 3, 4 and 8, nuclear enclosing layer 22 has a neckportion 22 a which is bonded to indwelling catheter 32, forming a secureconnector terminal 22 b. Indwelling catheter 32 has a proximal end 32 cincluding bulbous portion 32 b which is adapted to be coupled to nuclearaccess tube 106 inflation stylus 100, which is inserted through pathway40 in sealing valve core 28 of sealing valve assembly 26. Bulbousportion 32 b defines a bulbous portion that snaps into a correspondingbulbous region 32 e in sealing valve core 28. Bulbous portion 32 b issealingly affixed to the corresponding bulbous portion 32 e of sealingvalve core 28, forming a fluid-tight bond with sealing valve core 28.Proximal end 32 c of indwelling catheter 32 is in fluid communicationwith the distal end of nuclear access tube 106, within sealing valvecore 28.

Nuclear enclosing layer 22 is sealingly mounted on the shaft ofindwelling catheter 32. Preferably, neck portion 22 a of nuclearenclosing layer 22 is thermally or meltably bonded to indwellingcatheter 32. Connector terminal 22 b and indwelling catheter 32 are allpreferably made of melt compatible material. Connector terminal 22 b mayutilize a fie layer or “retaining collar” 22 c formed of mutuallybondable material that is slipped over neck portion 22 a of nuclearenclosing layer 22. Retaining collar 22 c is heated and crimped tosimultaneously meltably join neck portion 22 a of nuclear enclosinglayer 22, retaining collar 22 c, and indwelling catheter 32, makingconnector terminal 22 b a permanent fluid-tight seal.

Indwelling catheter 32 defines a lumen with side pore 32 a thereinlocated proximal to closed tip 32 d of indwelling catheter 32. Afterinflating nuclear prosthesis 10 within the nuclear space void of apatient, the lumen of indwelling catheter 32 can be permanentlyobstructed by a small sealing plug (not shown) introduced throughproximal end 32 c of indwelling catheter 32, and pushed into positionwith a guidewire (not shown) or other suitable positioning device.Pathway 40 of sealing valve core 28 collapses upon removal of inflationstylus 100, preventing back-up of the sealing plug within indwellingcatheter 32.

Referring to FIGS. 1D, 2D and 3D, delivery apparatus 200 is disclosed.Prior to insertion of delivery apparatus 200 into the patient, apercutaneous access device (not shown) provides an access way or annularfenestration(not shown) into the inter-vertebral disc space of thepatient, which is held open by an access cannula 202. Any percutaneousaccess device used for minimally invasive percutaneous procedures can beused to create the annular fenestration. Generally, such percutaneousaccess devices comprise a plurality of telescopically arranged cannulas(not shown). After creation of the annular fenestration, deliveryapparatus 200 can be delivered within access cannula 202. Deliveryapparatus 200 comprises a delivery cannula 204 with nuclear prosthesis10 loaded therein, and a release cannula 206. Delivery apparatus 200,including nuclear prosthesis 10 and delivery cannula 204 which housesnuclear prosthesis 10 is provided, assembled and hermetically sealed sothat loading or handling of nuclear prosthesis 10 is unnecessary duringinsertion and inflation thereof within the nuclear space void of thepatient.

Still referring to FIGS. 1D, 2D, and 3D, delivery apparatus 200 of thepresent invention has oval inner and outer cross-section conforming tothe cross sections of access cannula 202. Delivery apparatus 200comprises a delivery cannula 204 having a wall of uniform thicknessdefining a cylindrical inner passage having a substantially oval crosssection, and a substantially oval release cannula 206 located within theoval, cylindrical inner passage of delivery cannula 204. Inflationstylus 100 is slidably received within the oval release cannula 206.

Delivery apparatus 200 is slidably received internally of the accesscannula 202, and is selectively extendible and retractable relative toaccess cannula 202 to facilitate proper placement of nuclear prosthesis10 through the annular fenestration into the disc space void.

Referring to FIGS. 10 through 11B, delivery cannula 204 of deliveryapparatus 200 encloses release cannula 206, which is telescopicallyslidable over inflation stylus 100. As previously discussed, inflationstylus 100 includes three inflation tubes 102, 104 and 106 extendingfrom its tip. Inflation tubes 102, 104 and 106 are frictionally engagedto pathways 36 b 38 b and 40 (respectively) of sealing valve core 28. Ina preferred embodiment, nuclear access tube 106 has a bulbous ridge 106b formed at its mid aspect that mates with a corresponding bulbousregion 40 b formed along passageway 40. The frictional engagement, aswell as the engagement of bulbous ridge 106 b with the bulbous region 40b provides a firm attachment of inflation stylus 100 to sealing valvecore 28, while allowing inflation tubes 102, 104 and 106 to be withdrawnwhen sufficient force is applied to it.

The amount of force required to withdraw inflation stylus 100 fromnuclear prosthesis 10 may be chosen by selecting the rigidity andmodulus of elasticity forming sealing valve core 28 as well as selectingthe size and geometry of the pathways 36 b, 38 b and 40 and bulbousridge 106 b. Generally, the amount of force required to releaseinflation stylus 100 from sealing valve core 28 must be more than themaximum inflation pressure experienced at the connection duringinflation of nuclear prosthesis 10. It may be difficult to preciselycontrol the force required to withdraw inflation stylus 100 from sealingvalve core 28.

As may be appreciated, if this force is too great, sealing valve core 28may be dislodged through the annulotomy, possibly causing tearing of thenative annulus fibrosis. If the force required to withdraw inflationstylus 100 from sealing valve core 28 is too small, inflation stylus 100may become prematurely detached from sealing valve core 28 duringpressurizing and inflation of nuclear prosthesis 10.

Referring to FIGS. 10 through 12, in a preferred embodiment, the releaseof inflation stylus 100 from sealing valve core 28 is obtained byutilizing release cannula 206 placed coaxially around inflation stylus100. Release cannula 206 has a thick wall and a diameter smaller thanthe outer diameter of sealing valve core 28, such that its distal endengages sealing valve core 28 to, in effect, push sealing valve core 28away from inflation stylus 100. A screw drive mechanism (not shown) isthreadedly engaged with and coupled to the proximal end (not shown) ofinflation stylus 100 and release cannula 206 to achieve smooth,efficient, and predictable disengagement of inflation stylus 100 fromthe sealing valve core 28.

The screw drive mechanism provides a mechanical advantage forwithdrawing inflation stylus 100 from sealing valve core 28 at acontrolled rate. A coupler (not shown) at the proximal end of inflationstylus 100 is adapted to engage the proximal end (not shown) of releasecannula 206 to controllably extend and retract inflation stylus 100 andcontrol its maximum travel. This can be done while the tip of releasecannula 206 holds sealing valve core 28 stationary within annularenclosure 14. The extension and retraction capabilities of inflationstylus 100 (in unison or independent of release cannula 206) facilitateproper deployment and detachment of nuclear prosthesis 10 within thenuclear space void. Withdrawal of inflation stylus 100 may be achievedby merely turning a knob (not shown) on the screw drive mechanism, whichcauses inflation stylus 100 to retract axially with respect to releasecannula 206, while sealing valve core 28 is held in place by the tip ofrelease cannula 206, thereby selectively screw-engaging or disengagingrelease cannula 206.

The retracting motion continues until inflation tubes 102, 104 and 106are completely disengaged from pathways 36 b, 38 b and 40, respectively,of sealing valve core 28. The screw drive mechanism may include a wormdrive (not shown) that mates with teeth (not shown) formed on theexterior surface of inflation stylus 100 and release cannula 206.Clearly, a wide variety of mechanical linkages are available to extendand retract inflation stylus 100 and release cannula 206. It isparticularly advantageous to provide a mechanism which allowsindependent, as well as linked and coordinated movements.

The knob may also be rotationally twisted in one direction during theloading of nuclear prosthesis 10 into delivery apparatus 200. In thiscase, release cannula 206 and inflation stylus 100 are retracted as oneunit into delivery apparatus 200, pulling nuclear prosthesis 10 througha loading apparatus 300 and progressively radially compressing nuclearprosthesis 10 to a reduced-radius state until it is fully loaded withindelivery cannula 204 of delivery apparatus 200. When the knob isrotationally twisted in the opposite direction, release cannula 206 andinflation stylus 100 extend as one unit extruding nuclear prosthesis 10from the tip of delivery cannula 204 to achieve predictable andcontrolled incremental deployment within the nuclear space void.

Referring to FIGS. 1A, 2A and 3A, loading apparatus 300 has a firstloading block 302 and a second loading block 304 traversed bymirror-image funnel-shaped passageways 306 and 308, respectively. Thedistal end of delivery apparatus 200 fits snugly but slidably withinloading port 316 at a front end of first loading block 302. The apposingends of first loading block 302 and second loading block 204 have thegeneral size and configuration of an inflated nuclear prosthesis 10.Each funnel shaped passageway 306 and 308 of first loading block 302 andsecond loading block 304, respectively tapers down within each loadingblock 302 and 304 to a second, smaller configuration which has thegeneral cross-sectional oblong configuration of delivery cannula 204 ofdelivery apparatus 200, and runs for a short distance in loading blocks302 and 304, forming a smooth transition with the inner margin ofdelivery cannula 204 at the loading port 316 of first loading block 302.

Funnel passageways 306 and 308 of loading apparatus 300 define a tapereddiamond-shaped space that geometrically and plastically deforms nuclearprosthesis 10 from a generally round, inflated configuration, as it isbeing deflated and pulled in opposing directions (as indicated bydirection arrows 400 and 402) of the radial axis through the taperedfunnel shaped passageways 306 and 308, and then loaded into deliverycannula 204 of delivery apparatus 200, which has been inserted intoloading port 316 of first loading block 302.

Referring to FIGS. 1A through 3C, as nuclear prosthesis 10 is pulled andstretched in opposing directions 400 and 402 within the diamond-shapedpassageway defined by funnel shaped passageways 306 and 308, nuclearprosthesis is progressively radially approximated to a reduced-radiusstate. Simultaneously, annular enclosure 14 is deflated, approximatinginner margin 16 and outer margin 18 of annular enclosing layer 12 intothe thin substantially “C” shaped configuration, which assumes a moreacute curvature as nuclear prosthesis 10 is stretched.

Annular enclosing layer 12 is stretched in a radial directiondiametrically opposite to loading port 316 and delivery apparatus 200 bya traction band 322 removably wrapped around annular enclosing layer 12at a position diametrically opposite the position of loading port 316.In one embodiment, removable traction band 322 is a rubber band.However, any suitable band made of any suitable material can be used astraction band 322, so long as it allows for removable attachment toannular enclosing layer 12 and is capable of stretching nuclearprosthesis 10 in a direction diametrically opposite the directiondelivery apparatus 200 stretches nuclear prosthesis 10. As nuclearprosthesis 10 reaches the small end of the diamond-shaped passagewaydefined by funnel shaped passageways 306 and 308, annular enclosinglayer 12 is wrapped tightly and folded compactly around nuclearenclosing layer 22 and indwelling catheter 32, into the smallestpossible cross-section, and is withdrawn into delivery cannula 204 ofdelivery apparatus 200. The folded nuclear prosthesis 10 fits looselywithin delivery cannula 204, allowing achievement of unhindereddeployment into the nuclear space void.

The inner surfaces of loading blocks 302 and 304 are preferably linedwith a water-soluble lubricious hydrophilic coating (not shown) tolubricate the contact surfaces between loading blocks 302 and 304 andnuclear prosthesis 10 during loading thereof onto delivery apparatus200.

During the loading process, nuclear prosthesis 10 is deflated, stretchedand radially compressed so as to adopt a low-profile configurationwithin the delivery cannula. Referring to FIGS. 3A and 3D, foldednuclear prosthesis 10 is shown releasably attached to the distal end ofinflation stylus 100, which is surrounded by release cannula 206 andhoused within the delivery cannula 204. Delivery apparatus 200 passesthrough access cannula 202. As previously discussed, nuclear prosthesis10 is secured to inflation stylus 100, by way of inflation tubes 102,104 and 106 projecting from the distal tip of inflation stylus 100 andinserted into corresponding passageways 36 b, 38 b and 40, respectively,in sealing valve core 28 of nuclear prosthesis 10. When the inflationstylus 100—release cannula 206 assembly is retracted within deliverycannula 204, the loaded nuclear prosthesis 10 is pulled into thedelivery cannula 204.

It should be appreciated by one skilled in the art that once thedeflated nuclear prosthesis 10 is delivered into the nuclear space void,an inflation-assisting device (not shown) or fluid delivery apparatus(not shown) introduces the in-situ curable rubber into annular enclosure14 and the liquid and/or gas into nuclear enclosure 24. It should beunderstood to one of ordinary skill in the art that any device,apparatus and/or system suitable for injecting fluid can be used toinflate nuclear prosthesis 10 could be used. Furthermore, fluid can beinjected into nuclear prosthesis 10 manually using a syringe (not shown)connected to the tubes 102, 104 and 106 of inflation stylus 100.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitedsense. Various modifications of the disclosed embodiments, as well asalternative embodiments of the invention will become apparent to personsskilled in the art upon the reference to the description of theinvention. It is therefore contemplated that the appended claims willcover such modifications that fall within the scope of the invention.

1.-41. (canceled)
 42. A nuclear prosthesis for percutaneous implantationinto a de-nucleated intervertebral disc comprising: an inflatableannular enclosure comprising an annular enclosing layer having an outermargin, a center region, a fluid-tight annular inner space; areinforcement band; a sealing valve assembly in fluid communication withthe fluid-tight annular inner space, the scaling valve assemblycomprising a sealing valve core comprising resilient material and atleast partially secured to the annular enclosing layer; and a nuclearenclosure comprising a nuclear enclosing layer, and an inflatablefluid-tight nuclear inner space, wherein the nuclear enclosure is atleast partially situated within the annular enclosure.
 43. Theprosthesis of claim 42 wherein the inflatable annular enclosure furthercomprises an in situ curable elastomeric material.
 44. The prosthesis ofclaim 42 wherein the reinforcement band is associated with the outermargin of the annular enclosing layer.
 45. The prosthesis of claim 42wherein the sealing assembly is at least partially secured within thefluid-tight annular inner space.
 46. The prosthesis of claim 42 whereinthe nuclear enclosing layer is mounted on a indwelling catheterextending into the fluid-tight nuclear inner space and partiallyextending through the sealing valve core, with the indwelling catheterhaving a lumen for conduction of fluid along its length from within thesealing valve assembly and into the fluid-tight nuclear inner space. 47.The prosthesis of claim 46 wherein the nuclear enclosing layer issecured onto an interior surface of the annular enclosing layer and thesealing valve core and is inflatable within an open area in a centerregion of the annular enclosure.
 48. The prosthesis of claim 42 whereinmultiple open pathways are present within the sealing valve core thatprovide fluid-tight sealing for the annular enclosure and the nuclearenclosure.
 49. The prosthesis of claim 46 wherein the indwellingcatheter and the sealing valve core provide a sealing valve to theannular enclosure and the nuclear enclosure.
 50. The prosthesis of claim42 wherein the sealing valve is within the fluid-tight annular innerspace, and multiple open pathways are present within the sealing valvecore; each of the multiple open pathways passing through thereinforcement band.
 51. The prosthesis of claim 43 wherein the curableresilient material comprises a curable rubber or curable elastomer. 52.The prosthesis of claim 42 wherein the fluid-tight annular inner spacecontains a cured resilient material.
 53. The prosthesis of claim 42wherein the reinforcement band comprises a multi-layered reinforcementband.
 54. The prosthesis of claim 53 wherein the multi-layeredreinforcement band comprises textile reinforcing components.
 55. Theprosthesis of claim 42 wherein the fluid-tight nuclear inner space isinflatable with gas.
 56. The prosthesis of claim 54 wherein thefluid-tight nuclear inner space is inflated with air.
 57. The prosthesisof claim 42 where the annular enclosure is doughnut shaped.
 58. Theprosthesis of claim 42 wherein the prosthesis is implanted in a human.59. The prosthesis of claim 42 further comprising: a textilemulti-layered reinforcement band at least partially associated with theouter margin of the annular enclosing layer.
 60. The prosthesis of claim42 further comprising a sealing valve assembly in fluid communicationwith the fluid-tight annular inner space, the sealing valve assemblycomprising a sealing valve core comprising a resilient material and atleast partially secured to the annular enclosing layer, and a sealingvalve within the sealing valve core in fluid communication with thefluid-tight annular inner space.
 61. The prosthesis of claim 59 whereinthe fluid-tight nuclear inner space is air-tight and is inflatable byair, and wherein the fluid-tight annular inner space is inflatable by anin situ curable rubber material.
 62. A system for delivery and inflationof a nuclear prosthesis for percutaneous implantation into ade-nucleated intervertebral disc comprising: a nuclear prosthesiscomprising; an inflatable annular enclosure comprising an annularenclosing layer having an outer margin, a center region, and afluid-tight annular inner space; a reinforcement band; a sealing valveassembly in fluid communication with the fluid-tight annular innerspace, the sealing valve assembly comprising a sealing valve corecomprising resilient material and at least partially secured to theannular enclosing layer; and a nuclear enclosure comprising a nuclearenclosing layer, and an inflatable fluid-tight nuclear inner space,wherein the nuclear enclosure is at least partially situated within theannular enclosure. a delivery apparatus for percutaneously deliveringthe nuclear prosthesis, comprising; a delivery cannula, and a releasecannula; and an inflation stylus for filling a the nuclear prosthesis,the inflation stylus at least partially within the delivery cannula anddetachably connected to the prosthesis.
 63. The system of claim 62wherein: the inflation stylus comprises at least one of an annular inlettube defining a lumen; an annular outlet tube defining a lumen, and anuclear access tube defining a lumen, each of the annular inlet tube andthe annular outlet tube comprising a fluid-penetrable opening along itsdistal portion.
 64. The system of claim 63, further comprising: anindwelling catheter configured to be accessible to the nuclear accesstube of the inflation stylus, the indwelling catheter having afluid-penetrable opening for introduction of a fluid into the nuclearenclosure; and the sealing valve core further comprising: one or moreoutlet ports in fluid communication with the annular enclosing layer anddisposed laterally with respect to the indwelling catheter and receivingthe annular outlet tube of the inflation stylus; and an inlet port influid communication with the annular enclosing layer and disposedlaterally with respect to the indwelling catheter in an opposeddirection to the outlet port and configured to receive the annular inlettube.
 65. The nuclear prosthesis of claim 64 further comprising: apathway for receiving the nuclear access tube, the pathway extendingfrom the indwelling catheter through the annular enclosing layer; and aretaining ring adjacent to the annular enclosing layer and the annularreinforcement band.
 66. The nuclear prosthesis of claim 64 furthercomprising a pathway for receiving the nuclear access tube, the pathwayextending from the indwelling catheter through the annular enclosinglayer.
 67. The system of claim 64 wherein: the inlet port comprises apathway disposed alongside of the annular inlet tube and is in fluidcommunication with a first channel extending through the sealing valvecore and into the annular enclosure; the outlet port comprises a pathwaydisposed alongside of the annular outlet tube and is in fluidcommunication with a second channel extending through the sealing valvecore and into the annular enclosure; and the fluid-penetrable opening ofthe annular inlet tube is disposed along a side of the annular inlettube and aligns with a channel of the inlet port, the channel extendingthrough the sealing valve core into the annular enclosure; thefluid-penetrable opening of the annular outlet tube is disposed along aside of the annular outlet tube and aligns with a channel of the outletport, the channel extending into the annular enclosure; and thefluid-penetrable opening of the nuclear access tube is disposed at thedistal end of the nuclear access tube.
 68. The system of claim 66further comprising: a detachable fluid-tight connection between theindwelling catheter and the connection terminal, wherein the indwellingcatheter comprises a connection terminal at its proximal end, and thenuclear access tube comprises a corresponding connection bulb forinsertion into the connection terminal.
 69. The system of claim 68wherein the nuclear prosthesis is inflatable by: introduction of a fluidthrough the fluid-penetrable opening of the nuclear access tube and thefluid-penetrable opening of the indwelling catheter into the nuclearenclosure; introduction of a fluid through the fluid-penetrable openingof the annular inlet tube and the inlet port into the annular enclosure;and wherein the fluid-penetrable opening of the annular outlet tube isconfigured to receive a return volume of the fluid conducted into theannular enclosure through the outlet port.
 70. The system of claim 69wherein the delivery apparatus is insertable within a percutaneousaccess device, and slideably extendable and retractable within thepercutaneous access device.
 71. The system of claim 70 wherein therelease cannula of the delivery apparatus is at least partially disposedwithin the delivery cannula of the delivery apparatus and telescopicallyslideable over the inflation stylus to detach the inflation stylus fromthe nuclear prosthesis after delivery and inflation thereof.
 72. Thesystem of claim 71 wherein a release cannula engages the sealing valvecore to push the inflation stylus away from the nuclear prosthesis. 73.The system of claim 72 wherein the release cannula further comprises ascrew drive mechanism threadedly engaged to a proximal end of theinflation stylus and the release cannula, the screw drive mechanismconfigured to extend the release cannula against the sealing valve coreand to retract the inflation stylus.
 74. The system of claim 73 whereinthe sealing valve core further comprises: a nuclear mounting regionhaving a predefined annular slot and a predefined nuclear slot adjacentto the inner margin of the annular enclosing layer, the nuclear slotreceiving the indwelling catheter and a connector terminal of thenuclear enclosing layer; wherein the connector terminal comprises a neckportion of the nuclear enclosing layer, and a retaining collarencompassing the neck portion of the nuclear enclosing layer, theconnector terminal receiving and securing to the indwelling catheter tocreate a fluid-tight connection.
 75. The system of claim 74 wherein: theannular slot extends around a radial circumference of the sealing valvecore, and further defines an annular mounting region alongside of thesealing valve core adjacent to the outer margin of the annular enclosinglayer; and the sealing valve core has an outer diameter smaller than thediameter of the annular enclosing layer, and receives a portion of theinner margin of the annular enclosing layer along the nuclear mountingregion and a portion of the outer margin of the annular enclosing layeralong the annular mounting region, forming a fluid-tight connectionbetween the annular enclosing layer and the sealing valve core.
 76. Thesystem of claim 75 wherein the scaling valve core is secured to theannular enclosing layer by a retaining ring surrounding the sealingvalve core, the retaining ring receiving and crimping to the annularslot in the nuclear mounting region and the annular mounting region. 77.The system of claim 76 wherein the fluid conducted into the nuclearenclosure is from a liquid reservoir and the fluid conducted into theannular enclosure is a from a reservoir of curable resilient material.78. The system of claim 76 wherein the fluid conducted into the nuclearenclosure is from a gas reservoir and the fluid conducted into theannular enclosure is from a reservoir of curable rubber resilientmaterial.
 79. The system of claim 77 wherein a gas is present in thenuclear enclosure.
 80. The system of claim 62 further comprising aloading apparatus for loading the nuclear prosthesis within the deliverycannula.
 81. A system for delivery and inflation of a nuclear prosthesisfor percutaneous implantation into a de-nucleated intervertebral disccomprising: a nuclear prosthesis comprising; an inflatable annularenclosure and a nuclear enclosure wherein the nuclear enclosure is atleast partially situated within the annular enclosure; a deliveryapparatus for percutaneously delivering the nuclear prosthesis,comprising; a delivery cannula, and a release cannula; and an inflationstylus for inflating a the nuclear prosthesis, the inflation stylus atleast partially within the delivery cannula and detachably connected tothe nuclear prosthesis.
 82. The system of claim 81 wherein the inflationstylus further comprises at least one of: an annular inlet tube defininga lumen; an annular outlet tube defining a lumen, and a nuclear accesstube defining a lumen, each of the annular inlet tube and the annularoutlet tube comprising a fluid-penetrable opening along its distalportion.
 83. The system of claim 82 wherein the inflation stylus is influid communication with an indwelling catheter configured to beaccessible to the nuclear access tube and having an opening forintroduction of a fluid into the nuclear enclosure of the nuclearprosthesis.
 84. The system of claim 81, wherein the delivery apparatusfurther comprises a release cannula at least partially disposed withinthe delivery cannula.
 85. The system of claim 81 wherein in the deliveryapparatus further comprises a release cannula having a screw drivemechanism threadedly connected to a proximal end of the inflation stylusand the release cannula.
 86. An inflation stylus for in vivo inflationof a nuclear prosthetic device, the inflation stylus comprising at leastone of: an annular inlet tube defining a lumen; an annular outlet tubedefining a lumen, and a nuclear access tube defining a lumen, each ofthe annular inlet tube and the annular outlet tube comprising afluid-penetrable opening along its distal portion.
 87. The inflationstylus of claim 86 further comprising: a delivery apparatus forpercutaneously delivering a nuclear prosthesis, having a deliverycannula, wherein the inflation stylus is at least partially within thedelivery cannula.
 88. A delivery apparatus for delivery of a nuclearprosthesis for percutaneous implantation into a de-nucleatedintervertebral disc, the delivery apparatus comprising: a deliverycannula and a release cannula, wherein the release cannula is at leastpartially disposed within the delivery cannula.
 89. The deliveryapparatus of claim 88 wherein the release cannula comprises a proximalend and a screw drive mechanism threadedly connected to a proximal endof an inflation stylus.
 90. The delivery apparatus of claim 89 whereinthe inflation stylus is at least partially within the delivery cannula.91. The delivery apparatus of claim 89 wherein the inflation styluscomprises at least one of: an annular inlet tube defining a lumen; anannular outlet tube defining a lumen, and a nuclear access tube defininga lumen, each of the annular inlet tube and the annular outlet tubecomprising a fluid-penetrable opening along its distal portion.